1. Field of the Invention
The present invention relates to metal-insulator-metal (MIM) capacitors, and in particular to MIM capacitors having an improved capacitance.
2. Discussion of the Related Art
MIM capacitors generally comprise two metal plates separated by a layer of a dielectric material. A 3D MIM capacitor is discussed in paper titled High-Capacitance Cu/Ta2O5/Cu MIM Structure for SoC Applications Featuring a Single-Mask Add-on Process, T. Ishikawa et al., IEDM 2002. This 3D MIM structure comprises a trench in which layers of Ta, Al2O3, Ta2U5, Al2O3, and Ta have been deposited. Such a structure has an increased capacitive surface when compared to classic MIM capacitors and therefore provides an improved capacitance per unit area.
For some applications it would be desirable to provide a process of forming a MIM capacitor having improved capacitance per unit area when compared to conventional MIM capacitors or to the above-mentioned 3D MIM capacitor.